One of the most photographed spots in rural Catalonia, the town of Castellfullit de la Roca is set on a narrow basalt cliff at the foot of the Pyrenees mountain range. The unique shape of the cliff is due to the erosion of the two surrounding rivers, Fluvià and Toronell, on the remains of the cooled volcanic lava thousands of years ago. The medieval town is tiny, with less than one square kilometer to walk on, due to the confined space up on the 50-meter-high cliff. The volcanic-rock houses blend with the Renaissance-style buildings on the narrow pathways of this eye-catching town.